Do typhoons pull Indonesian smoke into the Pacific? A pre-registered test, and the record 2026 season
Abstract
In August to October 2026, during an El Niño with the highest Oceanic Niño Index for those months since 1950 (+2.46 °C), smoke from Indonesian fires spread over the western North Pacific while an active typhoon season was under way. Since 2012, typhoons have been described as drawing Maritime Continent smoke into the monsoon flow and out over the ocean, but this rests on case studies and field campaigns. Using open satellite, reanalysis, fire and ground data, and fixing the criteria of every test in writing before computation, this study asks whether typhoons robustly increase smoke export, whether 2026 was exceptional in the typhoon zone, and why. A typhoon-day increase in smoke inflow to a corridor east of the Philippines (128 to 150° E, 3 to 18° N), found in MERRA-2 for 2003 to 2026, failed a placebo test (p = 0.105) and did not replicate in 23 independent seasons (1980 to 2002). In the same corridor, August to October 2026 had the highest aerosol optical depth (AOD) of the VIIRS era (2012 to 2026) in both VIIRS satellites, 8% above 2015 in VIIRS SNPP. The lead was 21% for August to September, and 2026 ranked first in August and in September separately, while 2015 peaked in October. The excess was fine-mode smoke, and AERONET stations at the source confirmed 2026 above 2015. Fire radiative power over Indonesia as a whole was 29% lower than in 2015, but in eastern Indonesia, the source nearest the corridor, it was the highest of the period and three times the 2015 value in August. Winds and rainfall favoured the corridor, but no more than in 2015. The 2026 record reflects where and when Indonesia burned, not a typhoon effect on export.
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BibTeX
@misc{tai2026typhoons,
title = {{Do typhoons pull Indonesian smoke into the Pacific? A pre-registered test, and the record 2026 season}},
author = {Lik Ren Tai},
howpublished = {EarthArXiv},
year = {2026},
month = nov,
doi = {10.31223/x5cc0m},
url = {https://eartharxiv.org/repository/view/16013/},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Do typhoons pull Indonesian smoke into the Pacific? A pre-registered test, and the record 2026 season
AU - Lik Ren Tai
PY - 2026
DA - 2026/11/08
PB - EarthArXiv
DO - 10.31223/x5cc0m
UR - https://eartharxiv.org/repository/view/16013/
AB - In August to October 2026, during an El Niño with the highest Oceanic Niño Index for those months since 1950 (+2.46 °C), smoke from Indonesian fires spread over the western North Pacific while an active typhoon season was under way. Since 2012, typhoons have been described as drawing Maritime Continent smoke into the monsoon flow and out over the ocean, but this rests on case studies and field campaigns. Using open satellite, reanalysis, fire and ground data, and fixing the criteria of every test in writing before computation, this study asks whether typhoons robustly increase smoke export, whether 2026 was exceptional in the typhoon zone, and why. A typhoon-day increase in smoke inflow to a corridor east of the Philippines (128 to 150° E, 3 to 18° N), found in MERRA-2 for 2003 to 2026, failed a placebo test (p = 0.105) and did not replicate in 23 independent seasons (1980 to 2002). In the same corridor, August to October 2026 had the highest aerosol optical depth (AOD) of the VIIRS era (2012 to 2026) in both VIIRS satellites, 8% above 2015 in VIIRS SNPP. The lead was 21% for August to September, and 2026 ranked first in August and in September separately, while 2015 peaked in October. The excess was fine-mode smoke, and AERONET stations at the source confirmed 2026 above 2015. Fire radiative power over Indonesia as a whole was 29% lower than in 2015, but in eastern Indonesia, the source nearest the corridor, it was the highest of the period and three times the 2015 value in August. Winds and rainfall favoured the corridor, but no more than in 2015. The 2026 record reflects where and when Indonesia burned, not a typhoon effect on export.
ER -